1. Field of the Invention
The present invention relates to strip cutting apparatus which cuts segments from a strip. In particular, the present invention is an improvement to strip cutting apparatus such as a photographic paper cutter which includes a stepper motor for driving the strip and a movable blade for cutting the strip transversely to cut segments from the strip.
2. Description of the Prior Art
In commercial photographic processing operations, very high rates of processing must be achieved and maintained in order to operate profitably. To expedite the photographic processing, orders containing film of similar type and size are spliced together for developing. As many as 500 to 1000 rolls of 12, 20, 24, and 36 exposure film may be spliced together for processing and printing purposes.
After developing, the photographic images contained in the film negatives are printed in an edge-to-edge relationship on a continuous strip of photosensitive paper by a photographic printer. The photographic printer causes high intensity light to be passed through a negative and imaged onto the photographic paper. The photographic emulsion layer on the paper is exposed and is subsequently processed to produce a print of the image contained in the negative.
After a strip of print paper has been photoprocessed to produce prints, a photographic paper cutter cuts individual prints from the strip. The prints are then sorted by customer order and ultimately sent to the customer.
The desire for high rates of processing within commercial photographic processing operations has led to the development of extremely high speed automatic paper cutters. One example of an automatic paper cutter is the Pako PC305 paper cutter, which is capable of cutting over 25,000 prints per hour (i.e., over 7 prints per second). The following patent applications, which were all filed Sept. 29, 1977, and are assigned to Pako Corporation, the assignee of the present application, describe various portions of the Pako PC305 paper cutter: "Microprocessor Controlled Photographic Paper Cutter," Ser. No. 838,064 by G. Strunc and F. Laciak, now U.S. Pat. No. 4,128,887; "Paper Drive Mechanism for Automatic Photographic Paper Cutter," Ser. No. 837,987 by R. Diesch; "Multichannel Indicia Sensor for Automatic Photographic Paper Cutter," Ser. No. 837,986 by R. Diesch and G. Strunc, now U.S. Pat. No. 4,147,080; "Stepper Motor Control," Ser. No. 837,988 by G. Strunc; "Print and Order Totalizer for Automatic Photographic Paper Cutter," Ser. No. 838,065 by G. Strunc; " Paper Feed Control for Automatic Photographic Paper Cutter," Ser. No. 838,000 by R. Diesch and G. Strunc, now U.S. Pat. No. 4,150,711; "Photographic Paper Cutter with Automatic Paper Feed in the Event of Occasional Missing Cut Marks," Ser. No. 837,999 by G. Strunc; and "Knife Assembly for Photographic Strip Cutter," Ser. No. 837,998 by R. Diesch, now U.S. Pat. No. 4,112,801.
In order to provide the high speed and high accuracy required, most automatic photographic paper cutters use stepper motor drive systems to drive the paper strip in step increments. The digital nature of the stepper motor is particularly advantageous when used in conjunction with digital electronic controls such as a microprocessor.